First stage turbine housing for an air cycle machine

ABSTRACT

A housing of an air cycle machine includes a static seal portion, a main bore housing portion, a shroud pilot housing portion, and a thrust plate housing portion. The static seal portion is arranged about a central axis and defines static seal radius D 1 . The main bore housing portion is arranged about the central axis and circumscribes the shaft arranged along the central axis. The main bore housing defines central bore inner radius D 2 . The shroud pilot housing radius is arranged about the central axis and defines shroud pilot radius D 3 . The thrust plate housing portion is arranged about the central axis and defines insulator seal plate radius D 4 . A ratio D 1 /D 2  is 0.8394 to 0.8416, a ratio D 1 /D 3  is 0.4315 to 0.4322, a ratio D 1 /D 4  is 0.2517 to 0.2521, a ratio D 2 /D 3  is 0.5130 to 0.5146, a ratio D 2 /D 4  is 0.2993-0.3001, and a ratio D 3 /D 4  is 0.5828-0.5838.

BACKGROUND

The present invention relates to Air Cycle Machines (ACMs). ACMs may beused to compress air in a compressor section. The compressed air isdischarged to a downstream heat exchanger and further routed to aturbine. The turbine extracts energy from the expanded air to drive thecompressor. The air output from the turbine may be utilized as an airsupply for a vehicle, such as the cabin of an aircraft. ACMs may be usedto achieve a desired pressure, temperature, and humidity in the air thatis transferred to the environmental control system of the aircraft.

ACMs often have a three-wheel or four-wheel configuration. In athree-wheel ACM, a turbine drives both a compressor and a fan whichrotate on a common shaft. In a four-wheel ACM, two turbine sectionsdrive a compressor and a fan on a common shaft.

Airflow from one working fluid must be directed through a ram circuitconsisting of a heat exchanger and the fan section of the ACM. Airflowfrom a second working fluid must be directed into the compressorsection, away from the compressor section towards the heat exchanger,from the heat exchanger to the turbine or turbines, and from the finalturbine stage out of the ACM. In at least some of these transfers, it isdesirable to direct air radially with respect to the central axis of theACM. To accomplish this, rotating nozzles may be used to generate radialin-flow and/or out-flow.

ACMs often have more than one housing section. The housings used in anACM are used to contain airflow routed through the ACM, as well asrotating parts. Often, housing components are configured adjacent toseals and/or other housing components to achieve airflow containment.

SUMMARY

A housing of an air cycle machine includes a static seal portion, a mainbore housing portion, a shroud pilot housing portion, and a thrust platehousing portion. The static seal portion is arranged about a centralaxis and defines static seal radius D₁. The main bore housing portion isarranged about the central axis and circumscribes the shaft arrangedalong the central axis. The main bore housing defines central bore innerradius D₂. The shroud pilot housing radius is arranged about the centralaxis and defines shroud pilot radius D₃. The thrust plate housingportion is arranged about the central axis and defines insulator sealplate radius D₄. A ratio D₁/D₂ is 0.8394 to 0.8416, a ratio D₁/D₃ is0.4315 to 0.4322, a ratio D₁/D₄ is 0.2517 to 0.2521, a ratio D₂/D₃ is0.5130 to 0.5146, a ratio D₂/D₄ is 0.2993-0.3001, and a ratio D₃/D₄ is0.5828-0.5838.

An air cycle machine includes a fan section arranged around a shaft. Thefan section is capable of routing a first working fluid. A compressorsection is arranged next to the fan section and positioned around theshaft and is capable of compressing a second working fluid. A turbinesection is arranged next to the compressor section and positioned aroundthe shaft. The turbine section is capable of converting potential energyof the second working fluid into rotational energy. A heat exchanger iscapable of exchanging heat between the first working fluid and thesecond working fluid. A housing of an air cycle machine includes astatic seal portion, a main bore housing portion, a shroud pilot housingportion, and a thrust plate housing portion. The static seal portion isarranged about a central axis and defines static seal radius D₁. Themain bore housing portion is arranged about the central axis andcircumscribes the shaft arranged along the central axis. The main borehousing defines central bore inner radius D₂. The shroud pilot housingradius is arranged about the central axis and defines shroud pilotradius D₃. The thrust plate housing portion is arranged about thecentral axis and defines insulator seal plate radius D₄. A ratio D₁/D₂is 0.8394 to 0.8416, a ratio D₁/D₃ is 0.4315 to 0.4322, a ratio D₁/D₄ is0.2517 to 0.2521, a ratio D₂/D₃ is 0.5130 to 0.5146, a ratio D₂/D₄ is0.2993-0.3001, and a ratio D₃/D₄ is 0.5828-0.5838.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an air cycle machine.

FIG. 2 is a perspective view of a housing of the air cycle machine.

DETAILED DESCRIPTION

The dimensions of an air cycle machine housing are selected in order toachieve several goals. Reduced drag of rotating shaft on static shaftseal minimizes friction losses and transfers more turbine power to thecompressor and fan. Seal clearance is desirably minimized, in order tominimize compressor inlet flow lost through the seal. Shaft excursions,such as seals, result in intimate contact between shaft seal teeth andassociated seal lands. The seal clearance losses are balanced againstthe frictional losses of seal drag during shaft excursions. Clearance ismaintained between the rotating shaft teeth and the seal land to reduceor eliminate sub-synchronous vibrations in foil bearings of the aircycle machine. Further, the leakage from excursions such as seals isprevented from dumping into part of the bearing cooling flow path.Excessive leakage into this flowpath could result in a blockage ofcooling flow. Seal sizing prevents the excessive leakage that couldcause reduced bearing cooling flow and over-temperature of the bearingsurfaces.

Optimizing performance of a compressor and a turbine can be quitedifferent. For a compressor, the inlet air is at a lower pressure thanthe outlet air, but the opposite is true for a turbine. Also, thecompressor inlet air contains a high temperature, and the compressordischarge temperature is even greater. For the turbine, the inlet air isat a cool temperature and the outlet is at an even colder temperature.When the compressor and turbine parts are optimized, differentmethodologies are required for the turbine and compressor. If theturbine were designed using an the incorrect optimization technique,either the clearance would be too loose and cause poor turbineperformance or the seal clearance would be too tight and cause a sideloading of the foil bearings. In the specific instance of the sealclearance being too tight, the foil bearings would be excessively sideloaded and result in poor reliability or reduced load capability. Onefeature of this ACM is the use of the bearing clearances and seal sizesto prevent excessively side-loading the bearings without having anynegative impact on turbine performance or additional bearing cooling.

FIG. 1 is a cross-sectional view of ACM 2, which is a four-wheel ACM. Asshown in FIG. 1, ACM 2 includes fan section 4, compressor section 6,first stage turbine section 8, and second stage turbine section 10,which are all connected to shaft 12. Shaft 12 rotates about central axis14.

Fan section 4, compressor section 6, first stage turbine section 8, andsecond stage turbine section 10 are also connected to one another viashaft 12. Shaft 12 runs along central axis 14, and is connected to atleast compressor nozzle 26, first stage turbine nozzle 32, and secondstage turbine nozzle 38. Fan blades 20 may also be connected to shaft12.

When working fluid passes through ACM 2, it is first compressed incompressor section 6, and then expanded in first stage turbine section 8and second stage turbine section 10. Often, a first working fluid isheated or cooled in a heat exchanger (not shown) through which workingfluid is routed as it passes between compressor section 6 and firststage turbine section 8. First stage turbine section 8 and second stageturbine section 10 extract energy from the working fluid, turning shaft12 about central axis 14. Meanwhile, a second working fluid is routedthrough the same heat exchanger by fan section 4. For example, the firstworking fluid may be routed from a bleed valve of a gas turbine enginethrough compressor section 6, to a heat exchanger, to first stageturbine section 8, then to second stage turbine section 10, and then tothe environmental control system of an aircraft. The second workingfluid may be ram air that is pulled by fan section 4 through the sameheat exchanger to cool the first working fluid to a desired temperaturebefore routing of the first working fluid to the turbine sections 8 and10. By compressing, heating, and expanding the working fluid, the outputprovided at the second stage turbine 10 may be adjusted to a desiredtemperature, pressure, and/or relative humidity.

Fan section 4 includes fan inlet 16 and fan outlet 18. Fan inlet 16 isan opening in ACM 2 that receives working fluid from another source,such as a ram air scoop. Fan outlet 18 allows working fluid to escapefan section 4. Fan blades 20 may be used to draw working fluid into fansection 4.

Compressor section 6 includes compressor inlet 22, compressor outlet 24,compressor nozzle 26, and compressor blades 27. Compressor inlet 22 is aduct defining an aperture through which working fluid to be compressedis received from another source. Compressor outlet 24 allows workingfluid to be routed to other systems after it has been compressed.Compressor nozzle 26 is a nozzle section that rotates through workingfluid in compressor section 6. Compressor nozzle 26 directs workingfluid from compressor inlet 22 to compressor outlet 24 via compressorblades 27. Compressor nozzle 26 is a radial out-flow rotor.

First stage turbine section 8 includes first stage turbine inlet 28,first stage turbine outlet 30, first stage turbine nozzle 32, and firststage turbine blades 33. First stage turbine inlet 28 is a duct definingan aperture through which working fluid passes prior to expansion infirst stage turbine section 8. First stage turbine outlet 30 is a ductdefining an aperture through which working fluid (which has expanded)departs first stage turbine section 8. First stage turbine nozzle 32 isa nozzle section that rotates through working fluid in first stageturbine section 8. First stage turbine nozzle 32 cooperates with firststage turbine blades 33 to extract energy from working fluid passingtherethrough, driving the rotation of first stage turbine section 8 andattached components, including shaft 12, fan section 4, and compressorsection 6. First stage turbine nozzle 32 is a radial in-flow rotor.

Second stage turbine section 10 includes second stage turbine inlet 34,second stage turbine outlet 36, second stage turbine nozzle 38, andsecond stage turbine blades 39. Second stage turbine inlet 34 is a ductdefining an aperture through which working fluid passes prior toexpansion in second stage turbine section 10. Second stage turbineoutlet 36 is a duct defining an aperture through which working fluid(which has expanded) departs second stage turbine section 10. Secondstage turbine nozzle 38 is a nozzle section that cooperates with secondstage turbine blades 39 to extract energy from working fluid passingtherethrough, driving the rotation of second stage turbine section 10and attached components, including shaft 12, fan section 4, andcompressor section 6. In particular, second stage turbine nozzle 38 is aradial out-flow rotor. Working fluid passes from second stage turbineinlet 34 to cavity 35, where it is incident upon second stage turbinenozzle 38. Working fluid then passes between nozzle blades (not shown).Turbine nozzle 38 is stationary, and the nozzle vanes guide the flow foroptimum entry into the turbine rotor. The flow of causes turbine blades39 to rotate and turn shaft 12.

Shaft 12 is a rod, such as a titanium tie-rod, used to connect othercomponents of ACM 2. Shaft 12 includes a seal portion arranged partwayalong its length. Central axis 14 is an axis with respect to which othercomponents may be arranged.

Fan section 4 is connected to compressor section 6. In particular, fanoutlet 18 is coupled to compressor inlet 22. Working fluid is drawnthrough fan inlet 16 and discharged through fan outlet 18 by fan blades20. Working fluid from fan outlet 18 is routed to compressor inlet 22for compression in compressor section 6. Similarly, compressor section 6is coupled with first stage turbine section 8. Working fluid fromcompressor outlet 24 is routed to first stage turbine inlet 28.

Fan section 4 and compressor section 6 share housing 40. Housing 40encloses the moving parts and air paths through fan section 4 andcompressor section 6. The size and geometry of housing 40 define theflow of air through ACM 2. For example, housing 40 is arranged aboutshaft 12 so as to prevent excessive airflow around shaft 12. Inparticular, a static seal portion is included in shaft 12, directlyadjacent to static seal portion 44. The outer radius of the seal portionis set such that a seal is formed with static seal portion 44 of housing40. Thus, the outer radius of shaft 12 at the static seal portion isequal to or slightly less than static seal radius D1.

Housing 40 has specific dimensions to coordinate with adjacent housingsections, such as the housing surrounding turbine section 8. Housing 40includes main bore housing portion 42, static seal portion 44, shroudpilot housing 46, and thrust plate 48.

Static seal portion 44 is the portion of housing 40 that circumscribesshaft 12 at the longitudinal are at which shaft 12 includes a seal. Inthis way, static seal portion 44 prevents flow of fluid between housing40 and shaft 12. The radius of housing 40 from central axis 14 to staticseal portion 44 is illustrated as static seal radius D1. Static sealradius D1 is between 2.0724 cm and 2.07365 cm (0.8159 in. and 0.8164in.).

Main bore housing portion 42 is the portion of housing 40 thatcircumscribes shaft 12 so as to prevent excessive airflow around shaft12. The radius of housing 40 from central axis 14 to main bore housingportion 42 is illustrated as central bore inner radius D2. Central boreinner radius D2 is between 2.4638 cm and 2.4689 cm (0.9700 in. and0.9720 in.).

Shroud pilot housing 46 defines a portion of housing 40 at the pointwhere the radial distance between central axis 14 and housing 40 is at alocal minimum. Shroud pilot housing portion 46 is configured to matewith a complimentary feature, turbine housing 50. By coupling withturbine housing 50, shroud pilot housing 46 prevents working fluidpassing through the compressor inlet 22 from intermixing with compressedfluid at the compressor outlet 24. The radius of housing 40 from centralaxis 14 to shroud pilot housing 46 is illustrated as shroud pilothousing radius D3. Shroud pilot housing radius D3 is between 4.79805 cmand 4.80315 cm (1.8890 in. and 1.8910 in.).

Thrust plate 48 is a portion of housing 40 that extends between firststage turbine section 8 and second stage turbine section 10. Thrustplate 48 separates second stage turbine inlet 34 and cavity 35. Theradius from central axis 14 to thrust plate 48 is illustrated as thrustplate radius D4. Thrust plate housing radius D4 is between 8.22705 cmand 8.23215 cm (3.2390 in. and 3.2410 in.).

The ratios between static seal radius D1, central bore inner radius D2,shroud pilot housing radius D3, and thrust plate housing radius D4 canalso be set to reach optimized bearing cooling and seal leakagethroughout ACM 2. Optimized clearance of seals in ACM 2 also permitsproper operation of the shaft/rotor system. The following ratios arepreferable as between D1, D2, D3, and D4: D1/D2 is 0.8394 to 0.8416, aratio D1/D3 is 0.4315 to 0.4322, a ratio D1/D4 is 0.2517 to 0.2521, aratio D2/D3 is 0.5130 to 0.5146, a ratio D2/D4 is 0.2993-0.3001, and aratio D3/D4 is 0.5828-0.5838

FIG. 2 is a perspective view of housing 40, illustrating static sealradius D1, central bore inner radius D2, shroud pilot housing radius D3,and thrust plate radius D4. Components of ACM 2 of FIG. 1, including theadjacent housing of turbine section 8 and shaft 12, have been removed tomore clearly illustrate the specific dimensions of housing 40. Aspreviously described with respect to FIG. 1, a static seal portion D1,main bore housing radius D2, shroud pilot housing radius D3, and thrustplate housing radius D4 have specific ranges of dimensions that areoptimal.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments ofthe present invention.

A housing of an air cycle machine may include a static seal portionarranged about a central axis and configured to circumscribe a staticseal defined by a shaft arranged along the central axis. The static sealportion defines a static seal radius D₁. A main bore housing portion isarranged about the central axis and positioned longitudinally adjacentto the static seal portion. The main bore housing is configured tocircumscribe the shaft. The main bore housing defines a central boreinner radius D₂. A shroud pilot housing portion is arranged about thecentral axis. The shroud pilot housing portion defines a shroud pilotradius D₃. A thrust plate housing portion is arranged about the centralaxis and is configured to mate with an adjacent turbine sectioncomponent. The thrust plate housing portion defining an insulator sealplate radius D₄. The ratios as between D1, D2, D3, and D4 include D₁/D₂between 0.8394 to 0.8416, D₁/D₃ between 0.4315 to 0.4322, D₁/D₄ between0.2517 to 0.2521, D₂/D₃ between 0.5130 to 0.5146, D₂/D₄ between0.2993-0.3001, and D₃/D₄ between 0.5828-0.5838.

The housing of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations, and/or additional components.

The static seal radius may be between 2.0724 cm and 2.07365 cm. The mainbore housing radius may be between 2.4638 cm and 2.4689 cm. The shroudpilot housing radius may be between 4.79805 cm and 4.80315 cm. Thethrust plate housing radius may be between 8.22705 cm and 8.23215 cm.The turbine section component may be a turbine section housing. Theturbine section component may be a first stage turbine section housing.The shroud housing pilot portion may be configured to mate with theadjacent turbine section component.

An air cycle machine may include a shaft. The air cycle machine mayfurther include a fan section arranged around a portion of the shaft.The fan section is capable of routing a first working fluid. The aircycle machine includes a compressor section arranged adjacent to the fansection and positioned around the shaft. The compressor section iscapable of compressing a second working fluid. The turbine section isarranged adjacent to the compressor section and positioned around theshaft. The turbine section is capable of converting potential energy ofthe second working fluid to rotational energy. A heat exchanger iscapable of exchanging heat between the first working fluid and thesecond working fluid. A housing forms a part of both the fan section andthe compressor section. The housing includes a static seal portionarranged about a central axis and configured to circumscribe a staticseal defined by a shaft arranged along the central axis. The static sealportion defines a static seal radius D₁. A main bore housing portion isarranged about the central axis and positioned longitudinally adjacentto the static seal portion. The main bore housing is configured tocircumscribe the shaft. The main bore housing defines a central boreinner radius D₂. A shroud pilot housing portion is arranged about thecentral axis. The shroud pilot housing portion defines a shroud pilotradius D₃. A thrust plate housing portion is arranged about the centralaxis and is configured to mate with an adjacent turbine sectioncomponent. The thrust plate housing portion defining an insulator sealplate radius D₄. The ratios as between D1, D2, D3, and D4 include D₁/D₂between 0.8394 to 0.8416, D₁/D₃ between 0.4315 to 0.4322, D₁/D₄ between0.2517 to 0.2521, D₂/D₃ between 0.5130 to 0.5146, D₂/D₄ between0.2993-0.3001, and D₃/D₄ between 0.5828-0.5838.

The housing of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations, and/or additional components.

The second working fluid may pass through the heat exchanger locatedbetween the compressor section and the turbine section. The fan section,the compressor section, and the turbine section may be connected by theshaft to form a single spool. The static seal radius may be between0.8159 in. and 0.8164 in. The main bore housing radius may be between0.9700 in. and 0.9720 in. The shroud pilot housing radius may be between1.8890 in. and 1.8910 in. The thrust plate housing radius may be between3.2390 in. and 3.2410 in.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A housing of an air cycle machine, the housing comprising: a staticseal portion arranged about a central axis and configured tocircumscribe a static seal defined by a shaft arranged along the centralaxis, the static seal portion defining a static seal radius D₁; a mainbore housing portion arranged about the central axis and positionedlongitudinally adjacent to the static seal portion, the main borehousing configured to circumscribe the shaft, the main bore housingdefining a central bore inner radius D₂; a shroud pilot housing portionarranged about the central axis, the shroud pilot housing portiondefining a shroud pilot radius D₃; and an insulator seal plate housingportion arranged about the central axis and configured to mate with anadjacent turbine section component, the insulator seal plate housingportion defining an insulator seal plate radius D₄, wherein a ratioD₁/D₂ is 0.8394 to 0.8416, a ratio D₁/D₃ is 0.4315 to 0.4322, a ratioD₁/D₄ is 0.2517 to 0.2521, a ratio D₂/D₃ is 0.5130 to 0.5146, a ratioD₂/D₄ is 0.2993-0.3001, and a ratio D₃/D₄ is 0.5828-0.5838.
 2. Thehousing of claim 1 wherein the static seal radius is between 2.0724 cmand 2.07365 cm.
 3. The housing of claim 1 wherein the main bore housingradius is between 2.4638 cm and 2.4689 cm.
 4. The housing of claim 1wherein the shroud pilot housing radius is between 4.79805 cm and4.80315 cm.
 5. The housing of claim 1 wherein the insulator seal platehousing radius is between 8.22705 cm and 8.23215 cm.
 6. The housing ofclaim 1, wherein the turbine section component is a turbine sectionhousing.
 7. The housing of claim 1, wherein the turbine sectioncomponent is a first stage turbine section housing.
 8. The housing ofclaim 1, wherein the shroud housing pilot portion is configured to matewith an adjacent turbine section component.
 9. An air cycle machinecomprises: a shaft; a fan section arranged around a portion of theshaft, the fan section capable of routing a first working fluid; acompressor section arranged adjacent to the fan section and positionedaround the shaft, the compressor section capable of compressing a secondworking fluid; a turbine section arranged adjacent to the compressorsection and positioned around the shaft, the turbine section capable ofconverting potential energy of the second working fluid to rotationalenergy; a heat exchanger capable of exchanging heat between the firstworking fluid and the second working fluid; and a housing comprising: astatic seal portion arranged about a central axis and configured tocircumscribe a static seal defined by a shaft arranged along the centralaxis, the static seal portion defining a static seal radius D₁; a mainbore housing portion arranged about the central axis and positionedlongitudinally adjacent to the static seal portion, the main borehousing configured to circumscribe the shaft, the main bore housingdefining a central bore inner radius D₂; a shroud pilot housing portionarranged about the central axis, the shroud pilot housing portiondefining a shroud pilot radius D₃; and an insulator seal plate housingportion arranged about the central axis and configured to mate with anadjacent turbine section component, the insulator seal plate housingportion defining an insulator seal plate radius D₄, wherein a ratioD₁/D₂ is 0.8394 to 0.8416, a ratio D₁/D₃ is 0.4315 to 0.4322, a ratioD₁/D₄ is 0.2517 to 0.2521, a ratio D₂/D₃ is 0.5130 to 0.5146, a ratioD₂/D₄ is 0.2993-0.3001, and a ratio D₃/D₄ is 0.5828-0.5838.
 10. The aircycle machine of claim 9, wherein the second working fluid passesthrough the heat exchanger between the compressor section and theturbine section.
 11. The air cycle machine of claim 9, wherein the fansection, the compressor section, and the turbine section are connectedby the shaft to form a single spool.
 12. The housing of claim 9 whereinthe static seal radius is between 0.8159 in. and 0.8164 in.
 13. Thehousing of claim 9 wherein the main bore housing radius is between0.9700 in. and 0.9720 in.
 14. The housing of claim 9 wherein the shroudpilot housing radius is between 1.8890 in. and 1.8910 in.
 15. Thehousing of claim 9 wherein the insulator seal plate housing radius isbetween 3.2390 in. and 3.2410 in.